In Norse mythology, the Dokkalfar, or dark elves, are evil, subterranean counterparts to the light elves. Often, they are confused with the Svartálfar, (black elves).

As cited from this angelfire site [1] (http://www.angelfire.com/pa/WoundedDove/norse.html) which delves slightly into many Norse Mythos, containing the following pertaining to elves and the Dokkalfar type:

"Alf/Alfar/Elves

Elves are divided into three races.

1.)Ljosalfar - Light elves that live in Alfheim.

2.)Svatalfar - Dark elves that live in Svatalheim.

3.)Dokkalfar - Black elves/dwarfs that live in Nidavellir. Dokkalfar dwell in mounds, rocks, and are not fond of daylight. They are depicted as beautiful, pale, and human-like wights in noble clothes.

All elves are wise magicians. They have arrows that cause strokes and paralysis and they are thought to be the cause of sickness. Elves are tiny and sinister and take pleasure in acts of devilry (steal cattle and children). In the Middle East, it is believed that they weighed heavily upon the breast of sleepers giving them bad dreams."

Elves depicted in Norse mythology are more along the lines of todays "Christmas Elves", a tiny being, filled with trickery and mischeif. Dokkalfar being merely one of the subtypes. However the context we are more familiar with seeing elves in is the Tolkien-esque romantisized beautiful frail creatures who are usually portrayed as immortal.

Some documentation indicates that the Dokkalfar were not that of an elven race but, of a dwarven, cited above stating it was "elven/dwarven" however this documentation [2] (http://www.bookoffluids.com/summariatheologica.htm) Indicates they were dwarves, highlighted in this passage under the heading of "The Bad Guys":

"Dokkalfar and the Nibelungenlied: The Nibelungs/Dokkalfar were indeed a race of dwarf well known for their craftsmanship. They fashioned Freya’s necklace, Brisingamen in return for her favours. Their King was Alberich, who forswore love so that he might forge the Ring of Power which gives the bearer rulership of the world."

Another form of dark dwarf are the Duergar

As you can see this reference points towards Tolkien's work undoubtedly, as well as Lovecraft's writings on Cthulhu mythos.

See also: dark elf Drow Underdark